Oct flash DQS&data signals wave overshoot in DDR Mode

[yanglibin]

Hi expects,

Recently, wo found that wo chose 166MHz in DDR mode of MIMXRT1171,and the oct flash signal waveform would be overshot. Is this normal and can I choose 166MHz to use in DDR mode? If i can, how it needs to be optimized. Thanks a lot.

 

[riteshmpatel]

Hi Yang,

Hope you are doing well.

Apologies for delay in response.

Is this design simulated for Signal Integrity?

One can try adding series termination resistor on clock line and check with different values to decrease the overshoot and undershoot.

Thanks & Regards,

Ritesh M Patel

[yanglibin]

Hi Patel, Thanks for your reply ,the pictures above are screenshots of the DQS signal. We found that DQS signal wave would be overshoot in DDR mode with 166 MHz, in addition that the above phenomenon does not exist in SDR mode. What should we do to optimize this part in actual equipment?  Thanks & Regards.

[riteshmpatel]

Hi Yang,

Is there any series termination on the DQS line?

If not, one can try adding series termination resistor of low value on DQS line and observe the improvement on oscilloscope. 

Thanks & Regards,

Ritesh M Patel 

[yanglibin]

Hi Patel,

Thanks for your suggestions, we will try it.